The invention relates to an electrical switch for use in electric hand tools, such as electric drills, hammer drills, electric screwdrivers or the like, to switch the electric motor on and off and, if appropriate, to control the rotational speed of the electric motor.
DE-A 24 10 871 discloses an electrical switch with a housing in which a contact system is arranged. Mounted such that it can be moved on the housing is an actuating member which serves as a manual handle and which can be moved by the user into an actuating or operating position. In the operating position, the actuating member then acts to switch the contact system. In order to lock the actuating member in the operating position, the switch also has a locking device. The locking device comprises a slide that is connected to the actuating member and is guided on a side wall of the housing, and an actuating element that is mounted such that it can be moved on the side wall of the housing. By means of manual movement of the actuating element essentially perpendicularly with respect to the side wall of the housing, in the operating position of the actuating member, the actuating element can be brought to interact with the actuating member in order to lock the actuating member.
The actuating element for the known locking device is located on the side wall of the housing of the switch. In many cases, when the electric hand tool is used, manual handling of the actuating element can become arduous.
A switch for an electric tool, having a lateral locking device actuated by a plunger is also disclosed by U.S. Pat. No. 3,814,886. In addition, the switch has a changeover switch for reversing the direction of rotation of the electric tool. A rotary knob for actuating the changeover switch is arranged concentrically with a sleeve to accommodate the plunger. The rotation of the rotary knob about the sleeve moves a contact slide, which is connected to the rotary knob by means of a joint, as a result of which the changeover switch is actuated in order to reverse the polarity of the electric motor. The plunger for the locking device and the rotary knob for the changeover switch for reversing the direction of rotation are two separate actuating elements which differ from each other. Because of the lateral arrangement of the two actuating elements, again their manual operability can be made more difficult.
Furthermore, U.S. Pat. No. 4,097,703 discloses an electrical switch for electrical appliances in which an actuating member can be moved from an initial position into an operating position, so that, in the operating position, the actuating member acts to switch a contact system and to adjust a potentiometer. The switch has a movable actuating element which, during its movement, acts to actuate a first locking device on the switch. For electrical appliances with an electric motor which can be operated reversibly and which can be operated in two opposite directions of rotation, this switch has an additional switching element for changing over the direction of rotation. This additional switching element is actuated by a slide which is located on the rear of the switch, which is opposite the actuating member and the actuating element. Here, too, the actuation of actuating member, actuating element and slide is made more difficult for the user during the use of the electrical appliance. In particular, there is a risk of maloperation.
As a rule, so-called universal motors are used in electrical appliances. In these universal motors, the carbon brushes which feed the power to the armature via the collector are adjusted from the neutral position by a certain angle in order to achieve optimization of the motor operation in one direction of rotation. In order to achieve optimization in the other direction of rotation of the electric motor as well, a device for adjusting the carbon brushes can also be arranged on the electric motor.
DE 195 45 651 A1 discloses a device for adjusting the carbon brushes for the electric motor in accordance with its direction of rotation. This device for adjusting the carbon brushes has a pivotable carrier, on which brush holders for the carbon brushes which slip on the collector of the electric motor are arranged. The carrier can be pivoted manually by means of an actuating element. The electrical changeover switch for the direction of rotation of the electric motor can be integrated into this device for adjusting the carbon brushes at the same time.
In order to start up the electrical appliance, the user has to set the direction of rotation by means of the actuating element located on the device for adjusting the carbon brushes. In addition, in order to operate the electrical appliance, the actuating member of the electrical switch has to be actuated manually by the user. Both the electrical switch and the device for adjusting the carbon brushes are arranged at different points relatively far removed from each other on the electrical appliance, which means that when the electrical appliance is being used, manual handling of the actuating element can be made more difficult.
Finally, EP-A2-0 057 414 discloses an electric hand tool having a switch which has a trigger, a changeover switch for the direction of rotation of the electric hand tool additionally being arranged on the switch. The changeover switch can be actuated by means of a sliding handle, which is fixed to a lever which is arranged on the upper side of the trigger and can be pivoted about an axis. In addition, a brush carrier with brush holders for the electric motor is arranged in the housing of the electric hand tool such that it can be adjusted. When the lever for actuating the changeover switch is pivoted, at the same time the brush carrier is adjusted. To this end, there is a fork element on the lever, which interacts with a stub axle on the brush holder of the brush carrier.
In this known electric hand tool, two devices are actuated simultaneously by means of the lever as an actuating element, namely on the one hand the adjusting device for the brush carrier and on the other hand the changeover switch for the direction of rotation of the electric motor. However, the lever does not permit mutually independent actuation of the two devices, so that the manual handling of the actuating element is severely restricted.
Starting from EP-A2-0 057 414, the invention is based on the object of developing the electrical switch for an electrical appliance further in such a way that the operation becomes more simple and more convenient for the user.
In a generic electrical appliance, this object is achieved by an electrical switch and a movable actuating element. The electrical switch has an actuating member that can be moved between an initial position and an operating position in a direction of movement. The actuating member, in the operating position, acts to switch a contact system or to adjust a potentiometer. The movable actuating element is arranged in an immediate vicinity of the actuating member. The actuating element, during movement, acts to actuate a first device and a second device. The actuating element includes a first part being mounted such that it can be moved in a second direction and a second part that can be moved both with the first part in the second direction and also in a first direction that is different from the second direction such that the first device is actuated when the actuating element is moved in the first direction, and the second device is actuated when the actuating element is moved in the second direction.
One of these two directions may lie within an angular range of less than +/xe2x88x9290 degrees in relation to the direction of movement of the actuating member. The angle in relation to the direction of movement of the actuating member is preferably up to a maximum of +/xe2x88x9215 degrees. In particular, the actuating element can be moved approximately in the direction of the actuating member.
For the purpose of particularly good handling, the actuating element adjusting the carbon brushes. In addition, in order to operate the electrical appliance, the actuating member of the electrical switch has to be actuated manually by the user. Both the electrical switch and the device for adjusting the carbon brushes are arranged at different points relatively far removed from each other on the electrical appliance, which means that when the electrical appliance is being used, manual handling of the actuating element can be made more difficult.
The invention is based on the object of developing the electrical switch further in such a way that the operation becomes more simple and more convenient for the user.
In a generic electrical switch, this object is achieved by the characterizing features of claim 1.
The electrical switch according to the invention has a movable actuating element which is arranged in the immediate vicinity of the actuating member. When the actuating element is moved, this acts to actuate a first device on the switch. In addition, by means of the actuating element, a further, second device can be actuated, so that the actuating element represents a type of multifunctional lever. Further refinements of the invention are the subject matter of the subclaims.
In order to actuate the first device, the actuating element can be moved in a first direction and, in order to actuate the second device, can be moved in a second direction, the two directions being different. One of these two directions may lie within an angular range of less than +/xe2x88x9290 degrees in relation to the direction of movement of the actuating member. The angle in relation to the direction of movement of the actuating member is preferably up to a maximum of +/xe2x88x9215 degrees. In particular, the actuating element can be moved approximately in the direction of the actuating member.
For the purpose of particularly good handling, the actuating element can be arranged directly on the upper side of the actuating member, specifically approximately at the transition between the housing body and the handle of the electric tool. In this case, the actuating element is designed as a push button, lever or the like, while the actuating member of the switch is a trigger. The actuating element can then be moved by being pressed essentially in the direction of movement of the trigger.
If one of the two devices is a locking device, then the actuating element for actuating the locking device can be moved in a direction differing from the perpendicular to the direction of movement of the actuating member. It is often the case that the electric tool can be operated both in the clockwise and in the counterclockwise direction. It is then obvious for the electrical switch to include a changeover switch for the clockwise/counterclockwise rotation of the electric tool as one of the two devices. The changeover switch has a changeover lever which is mounted such that it can be pivoted by up to about +/xe2x88x9215 degrees, for example, with respect to the direction of movement of the actuating member. Likewise, it is obvious to design the changeover lever for the clockwise/counterclockwise rotation as an actuating element for the locking device at the same time. The changeover lever can then be moved in its longitudinal direction for the purpose of locking. The changeover lever can be configured in two parts, in such a way that a first part can be pivoted and the other, second part can both be pivoted with the first part and can be moved linearly, counter to a restoring force, approximately radially with respect to the pivoting movement.
In a development, the locking device has a blocking element that can be moved by means of the actuating element. The blocking element is mounted such that it can be moved on the housing of the switch and can be brought by the actuating element into engagement with the movement path of the actuating member in order to lock the actuating member. The blocking element is further provided with a hook which, in order to lock, acts on a blocking face, an undercut or the like on the actuating member. Of course, the hook can also act on a part connected to the actuating member, such as a slide guided laterally on the housing of the switch. Because of the interaction between the hook and the blocking face, the return movement of the actuating member effected by a restoring force in the operating position is prevented, and therefore the actuating member is locked in the operating position.
In one embodiment, the blocking element can be designed as a spring-loaded slide element that is mounted such that it can be moved linearly on a housing part of the switch. In this case, it is obvious to arrange the housing part at the transition between the walls of the housing which are assigned to the changeover switch for the clockwise/counterclockwise rotation and the actuating member. The slide element is guided in the housing part approximately parallel to the wall of the housing facing the actuating member. Furthermore, the slide element has a hook at the first end, which faces away from the wall of the housing that is assigned to the changeover switch for the clockwise/counterclockwise rotation. A wedge face on the actuating element, which is located in particular on the linearly movable, second part of the changeover lever, interacts with the second end of the slide element, which faces the wall of the housing that is assigned to the changeover switch for the clockwise/counterclockwise rotation. As a result, the slide element is displaced by the movement of the actuating element such that, in order to lock, the hook acts on a blocking face on the actuating member, if appropriate a blocking face configured like a shoulder, in the operating position of the actuating member.
In another embodiment, the blocking element is designed as a lever element that is mounted such that it can be rotated on the housing of the switch, for example on the wall of the housing that is assigned to the changeover switch for the clockwise/counterclockwise rotation. From the lever element there projects approximately perpendicularly an arm which extends approximately parallel to the wall of the housing facing the actuating member, and has a hook. A cam on the actuating element, which is located in particular on the linearly movable, second part of the changeover lever, engages in a slotted guide on the lever element. As a result, during the movement of the actuating element, the lever element is pivoted such that the hook, in order to lock, engages behind a blocking face on the actuating member, which is located on the lateral slide, for example, in the operating position of the actuating member.
Furthermore, one of the two devices may be a device for adjusting the carbon brushes for the electric motor, it being possible for this device to be adjusted by means of the movable actuating element. The device for adjusting the carbon brushes can have a pivotable carrier to accommodate the brush holders, a coupling element being arranged between the actuating element and the carrier. The coupling element can be designed in the manner of a gear mechanism or can comprise a toggle lever, tilting lever, a tilting detent mechanism or the like.
In particular, in this case it is also preferred for the actuating element for the device for adjusting the carbon brushes to be designed in the manner of a multifunctional lever. In addition to actuating the device for adjusting the carbon brushes, using this multifunctional lever, the switch for reversing the direction of rotation can be switched at the same time, and the actuation of a locking device for the actuating member in the operating position can be performed.
The advantages achieved by the invention consist in particular in that there is only one actuating element for a number of functions, for example for the locking, adjustment of the carbon brushes and changing over the direction of rotation. This results, on the one hand, in a considerable saving in costs. On the other hand, at the same time the ergonomics for the user when handling the electrical appliance is increased, and the aforementioned functions of the switch can be operated more conveniently for the user. Otherwise, maloperation by the user is also avoided, and the risks of an accident when using the electrical appliance are reduced. For example, changing over the direction of rotation can be blocked by the actuating element in a simple way if the actuating member of the switch is actuated.
In addition to the actuating member of the switch, the actuating element for the locking device and/or for the direction-of-rotation changeover switch and/or for the device for adjusting the carbon brushes can also be accommodated in the handle of the electrical appliance. At the same time, the handle which accommodates the switch and belongs to the electric tool can advantageously be configured to be symmetrical. In particular, it should be emphasized that, in particular, the locking action is equally suitable for right-handed and left-handed people, which is not the case in previous switches.
In addition, no additional opening is needed in the handle of the electric tool, such as was previously needed for the actuating element of the locking device and/or the adjusting device for the carbon brushes and/or for the direction-of-rotation changeover switch. As a result, not only is a more pleasing appearance of the electrical appliance or of the handle achieved, but also improved protection against the penetration of foreign bodies, such as dust, humidity or the like, into the electrical appliance. This also prevents premature failure of the electrical appliance and/or of the switch and/or of the aforementioned devices on the switch, and their service life is increased.